Ankle sprains typically result from an incidence of either excessive inversion or excessive eversion. Inversion, which is the more common injury cause, is characterized as internal rotation of the ankle joint. Eversion is characterized as external rotation of the ankle joint. Movement of the midfoot is also associated with inversion and eversion.
For example, in the typical ankle injury, an off-centered force, such as landing from a jump with the foot turned or experiencing a strong side-directed impact on the lower leg with the foot planted, causes the foot to invert or evert relative to the lower leg. As with other body joints, the ankle joint is held together, supported and cushioned by a number of non-bony or soft tissues, such as muscles, ligaments, tendons, and cartilage. When the off-centered force results in inversion or eversion of the foot relative to the lower leg in excess of the natural limits of the soft tissue structures, soft tissue damage of varying degrees of severity occurs. Such injuries can include stretching or tearing of those soft tissues and, if severe enough, damage or fracture to the bones which make up the ankle joint, lower leg and foot.
Ankle supports are often worn as treatment for an ankle sprain or to prevent an ankle sprain. Desirably, an ankle support is lightweight, compact so as to be able to be worn inside a shoe, supports the ankle and foot to limit inversion and eversion, but does not otherwise limit the flexion motions associated with the toe-up and toe-down motions of a normal gait. Prior devices have disadvantages in regards to one or more of these considerations and improvement is desired.